The present disclosure relates to a circuit, a voltage control oscillator, and an oscillation frequency control system.
In the past, a wireless communication device such as a mobile phone and a television broadcasting receiver includes a phase locked loop (PLL) and a mixer circuit to frequency-convert a high-frequency signal into an intermediate frequency signal. The mixer circuit uses a local oscillation signal generated by the PLL to convert a high-frequency signal into an intermediate frequency signal and outputs the converted signal.
The PLL includes a voltage control oscillator (VCO) that generates a local oscillation signal depending on control voltage. As shown in FIG. 14, as the VCO, a unit capacitance including an inductor L and a capacitor C is normally used (see, for example, Japanese Patent Application Laid-open No. 2013-089997).